1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
|
#!/usr/bin/python
#
# Copyright (C) 2016 Google, Inc
# Written by Simon Glass <sjg@chromium.org>
#
# SPDX-License-Identifier: GPL-2.0+
#
import command
import fdt
from fdt import Fdt, NodeBase, PropBase
import fdt_util
import sys
# This deals with a device tree, presenting it as a list of Node and Prop
# objects, representing nodes and properties, respectively.
#
# This implementation uses the fdtget tool to access the device tree, so it
# is not very efficient for larger trees. The tool is called once for each
# node and property in the tree.
class Prop(PropBase):
"""A device tree property
Properties:
name: Property name (as per the device tree)
value: Property value as a string of bytes, or a list of strings of
bytes
type: Value type
"""
def __init__(self, node, name, byte_list_str):
PropBase.__init__(self, node, 0, name)
if not byte_list_str.strip():
self.type = fdt.TYPE_BOOL
return
self.bytes = [chr(int(byte, 16))
for byte in byte_list_str.strip().split(' ')]
self.type, self.value = self.BytesToValue(''.join(self.bytes))
class Node(NodeBase):
"""A device tree node
Properties:
name: Device tree node tname
path: Full path to node, along with the node name itself
_fdt: Device tree object
subnodes: A list of subnodes for this node, each a Node object
props: A dict of properties for this node, each a Prop object.
Keyed by property name
"""
def __init__(self, fdt, offset, name, path):
NodeBase.__init__(self, fdt, offset, name, path)
def Scan(self):
"""Scan a node's properties and subnodes
This fills in the props and subnodes properties, recursively
searching into subnodes so that the entire tree is built.
"""
for name, byte_list_str in self._fdt.GetProps(self.path).iteritems():
prop = Prop(self, name, byte_list_str)
self.props[name] = prop
for name in self._fdt.GetSubNodes(self.path):
sep = '' if self.path[-1] == '/' else '/'
path = self.path + sep + name
node = Node(self._fdt, 0, name, path)
self.subnodes.append(node)
node.Scan()
def DeleteProp(self, prop_name):
"""Delete a property of a node
The property is deleted using fdtput.
Args:
prop_name: Name of the property to delete
Raises:
CommandError if the property does not exist
"""
args = [self._fdt._fname, '-d', self.path, prop_name]
command.Output('fdtput', *args)
del self.props[prop_name]
class FdtFallback(Fdt):
"""Provides simple access to a flat device tree blob using fdtget/fdtput
Properties:
See superclass
"""
def __init__(self, fname):
Fdt.__init__(self, fname)
if self._fname:
self._fname = fdt_util.EnsureCompiled(self._fname)
def GetSubNodes(self, node):
"""Returns a list of sub-nodes of a given node
Args:
node: Node name to return children from
Returns:
List of children in the node (each a string node name)
Raises:
CmdError: if the node does not exist.
"""
out = command.Output('fdtget', self._fname, '-l', node)
return out.strip().splitlines()
def GetProps(self, node):
"""Get all properties from a node
Args:
node: full path to node name to look in
Returns:
A dictionary containing all the properties, indexed by node name.
The entries are simply strings - no decoding of lists or numbers
is done.
Raises:
CmdError: if the node does not exist.
"""
out = command.Output('fdtget', self._fname, node, '-p')
props = out.strip().splitlines()
props_dict = {}
for prop in props:
name = prop
props_dict[prop] = self.GetProp(node, name)
return props_dict
def GetProp(self, node, prop, default=None, typespec=None):
"""Get a property from a device tree.
This looks up the given node and property, and returns the value as a
string,
If the node or property does not exist, this will return the default
value.
Args:
node: Full path to node to look up.
prop: Property name to look up.
default: Default value to return if nothing is present in the fdt,
or None to raise in this case. This will be converted to a
string.
typespec: Type character to use (None for default, 's' for string)
Returns:
string containing the property value.
Raises:
CmdError: if the property does not exist and no default is provided.
"""
args = [self._fname, node, prop, '-t', 'bx']
if default is not None:
args += ['-d', str(default)]
if typespec is not None:
args += ['-t%s' % typespec]
out = command.Output('fdtget', *args)
return out.strip()
@classmethod
def Node(self, fdt, offset, name, path):
"""Create a new node
This is used by Fdt.Scan() to create a new node using the correct
class.
Args:
fdt: Fdt object
offset: Offset of node
name: Node name
path: Full path to node
"""
node = Node(fdt, offset, name, path)
return node
|
